Suspension stop device

ABSTRACT

The invention concerns a suspension stop device, for a motor vehicle driving wheels, comprising a filtering block, consisting of an upper housing fixed relative to the vehicle body and co-operating with a lower housing mobile in rotation about a shock absorber rod and supporting a suspension spring, and a ball bearing. Said upper ( 21 ) and lower ( 23 ) housings are made of thermoplastic material and have opposite surfaces hollowed out in a circle, about the rotation axis (d) of the shock absorber rod ( 24 ), to receive a raceway for the ball bearing ( 22 ). The upper housing ( 21 ) further incorporates an impact stop ( 42 ) moulded around the leading stop ( 41 ) of the shock absorbing device, and the thermoplastic structure of the upper housing ( 21 )is reinforced by a ring ( 45 ) made of overmoulded elastomer.

[0001] The present invention relates to a suspension stop device,intended in particular for suspension systems of the McPherson type forthe steered wheels of a motor vehicle.

[0002] The suspension devices of motor vehicles generally contain asuspension-stop rolling bearing whose function is to transmit the axialand radial forces resulting from compression of the spring and at thesame time to permit practically frictionless rotation between the springand the vehicle body, this rotational movement of the spring takingplace while the steered wheels are being turned and during variations ofcompression of the spring by a winding-up effect of the coils.

[0003] A current solution, whose view in axial section is illustrated inFIG. 1, generally contains two components, a suppression block 1,intended to suppress the movements of the shock-absorber rod 2 and ofthe spring 6 relative to the body 3 of the vehicle along the axis Δ ofthe rod, and a ball bearing 4, maintained in a housing 5, intended totransmit the displacements of spring 6 in a plane P.

[0004] Suppression block 1 is made of rubber 10 or elastomer, bonded toa sheet-metal frame 11. It is integral with body 3, with which it is incontact by a bolt or other means.

[0005] Ball bearing 4 is seated between two bearing rings 5 forming ahousing, of steel, for example, upper ring 51 being fixed and integralwith the vehicle, while lower ring 52 is rotationally movable. Thislower ring 52 also functions as support for suspension spring 6 of thedevice.

[0006] Shock-absorber rod 2 is fixed to the suppression block by a nut7.

[0007] This current structure of a suspension stop device has a fairlylarge number of parts of different nature, which must be manufacturedthen assembled, resulting in a relatively complex and expensive device.

[0008] The present invention proposes to replace the current structureof the metal suppression block to which the rubber is bonded by athermoplastic structure that, in addition to suppressing vibrations andnoise, performs the function of a ball-bearing housing and the functionof a bump stop, thus reducing the number of parts of the suspension stopdevice and therefore its cost price.

[0009] For that purpose the object of the invention is a suspension stopdevice for the driving wheels of a motor vehicle, comprising on the onehand a suppression block composed of an upper case fixed relative to thevehicle body and cooperating with a lower case that can moverotationally around a shock-absorber rod and serving as support for asuspension spring, and on the other hand a ball bearing, characterizedin that the said upper and lower cases are made of thermoplasticmaterial and have opposite faces containing a circular hollow around theaxis of rotation of the shock-absorber rod in order to receive a racewayin the ball bearing, the upper case also integrating a bump stop moldedaround the striking stop of the shock-absorbing device, and in that thethermoplastic structure of the upper case is reinforced by a crown ofovermolded elastomer.

[0010] According to another characteristic, the two upper and lowercases of the suppression block are made of fiberglass-reinforcedthermoplastic material.

[0011] Other characteristics and advantages of the invention will becomeapparent on reading the description of a practical example illustratedby the following figures, which are, in addition to the alreadydescribed FIG. 1:

[0012]FIG. 2: a view in axial section of a suspension stop deviceaccording to the invention;

[0013]FIG. 3: a partial view in axial section of the suppression blockof the device according to FIG. 2;

[0014]FIG. 4: a perspective view of the upper case of the suppressionblock according to the invention.

[0015] The different elements identified by like reference symbols inthe different figures perform like functions in order to achieve likeresults.

[0016] As FIGS. 2 and 3 show, a suspension stop device for the steeredwheels of a motor vehicle is composed of a suppression block 20 made ofthermoplastic material of polyamide 6 type, which can be loaded withfibersglass to reinforce the structure. This suppression block iscomposed of an upper case 21 and lower case 23, whose opposite facescontain circular hollows in order to achieve the additional function ofraceway for the ball bearing 22, seated between these two cases, whichare solids of revolution around the axis δ of shock-absorber rod 24. Itis possible to insert a metal raceway in two parts, an upper part 31 anda lower part 32, seated respectively against the opposite faces of theupper and lower cases, serving as a more rigid cage for the balls 22.This raceway can be of deep drawn sheet metal.

[0017] To maintain these two cases firmly together, one below the other,upper case 21 is provided with a plurality of clips or catches 25 on itsperiphery, cooperating with a groove 26 machined on the circumference oflower case 23.

[0018] Ball bearing 22 ensures that lower case 23 can rotate relative toupper case 21 by virtue of a lubricant in which the balls are immersed.To ensure that this lubricant does not flow out of the raceway and thatdust or mud cannot contaminate the said raceway, the opposite faces ofthe two cases are each provided with at least one circular baffle 27cooperating with that of the other case to form at least one seal.

[0019] Uppercase 21 of suppression block 20 is obviously provided with acentral aperture 30, along the axis of shock absorber rod 24 and whichhas a diameter adjusted to that of the said rod around which it isplaced.

[0020] Upper case 21 of the suppression block performs a third function,that of a bump stop, progressively blocking the penetration of the bodyof the shock absorber against a striking stop 41 when the shock absorberarrives at the end of its deflection. For this purpose, the upper caseis provided with a molded base 42 which acts as a bump stop and whosebore, according to one embodiment, has a diameter larger than that ofits upper part, so that it surrounds striking stop 41.

[0021] Lower case 23 of the suppression block also serves to support theupper end of suspension spring 29 of the device, and it is provided withan aperture 40 whose diameter is larger than that of aperture 30 ofupper case 21 for the purpose of accommodating bump stop 42 of uppercase 21. The support surface in contact with the spring can be coveredwith a sole 49 of elastomer.

[0022] A protective bellows 43 surrounds shock absorber rod 24 as wellas striking stop 41, and its upper end 44 is wedged between the top ofthis striking stop and upper case 21.

[0023] To improve the suppression character of plastic block 20assembled in this way, the plastic structure of upper case 21 isreinforced by a crown 45 of overmolded rubber or elastomer, providedwith an axial bore adapted to the diameter of shock absorber rod 24.This crown advantageously suppresses vibrations and noise. It is fixedto plastic upper case 21 by bonding agent or adhesive.

[0024] In order to ensure leaktightness of the raceway of ball bearing22, rubber crown 45 is provided with at least six wells 46, disposed ingroups of two wells on three radii offset by 120°. These wells aredesigned to be seated in six channels drilled vertically in upper case21 of suppression block 20 and thus to form two concentric sealingannuli. These wells are overmolded at the same time as the crown, duringmanufacture thereof. In addition, these channels serve as anchoringpoints for the rubber crown on the upper part of upper case 21 of thesuppression block.

[0025]FIG. 4 is a perspective view from below of thermoplastic uppercase 21.

[0026] To maintain shock absorber rod 24 in the body 48 of the vehicleby a nut 28 tightened around its axis δ, it is necessary to place acylindrical metal distance piece 47 along rod 24, between it and uppercase 21 and rubber crown 45 of suppression block 20.

[0027] A suspension stop device designed according to the invention iscomposed of a reduced number of parts that can be easily made andassembled. The advantage of replacing a suppression block of rubber andsheet metal by rubber adhering to a thermoplastic structure is that theproblems of corrosion are eliminated and the total weight of the deviceis reduced.

1. A suspension stop device for the driving wheels of a motor vehicle,comprising on the one hand a suppression block composed of an upper casefixed relative to the vehicle body and cooperating with a lower casethat can move rotationally around a shock-absorber rod and that servesas support for a suspension spring, and on the other hand a ballbearing, characterized in that the said upper and lower cases (21, 23)are made of thermoplastic material and have opposite faces containing acircular hollow around the axis (δ) of rotation of the shock-absorberrod (24) in order to receive a raceway designed for the ball bearing(22), the upper case (21) also integrating a bump stop (42) moldedaround the striking stop (41) of the shock-absorbing device, and in thatthe thermoplastic structure of the upper case (21) is reinforced by acrown (45) of overmolded elastomer.
 2. A suspension stop deviceaccording to claim 1, characterized in that the two upper and lowercases (21, 23) of the suppression block (20) are made offiberglass-reinforced thermoplastic material.
 3. A suspension stopdevice according to one of claims 1 or 2, characterized in that theupper case (21) of the suppression block (20) is provided with aplurality of clips (25) on its periphery, designed to cooperate with agroove (26) machined on the circumference of the lower case (23).
 4. Asuspension stop device according to one of claims 1 or 2, characterizedin that the opposite faces of the upper and lower cases (21, 23) of thesuppression block (20) are each provided with at least one circularbaffle (27) cooperating with that of the other case to form at least oneseal.
 5. A suspension stop device according to one of claims 1 to 4,characterized in that the upper case (21) of the suppression block isprovided with a molded base which acts as a bump stop and whose bore hasa diameter larger than that of its upper part surrounding theshock-absorber rod (24), so that it surrounds striking stop (41).
 6. Asuspension stop device according to claim 1, characterized in that theelastomeric crown (45) reinforcing the upper case (21) of thesuppression block (20) is provided with at least six wells (46),disposed in groups of two wells on three radii offset by 120° intendedto be seated in six channels drilled vertically in the upper case (21)of thermoplastic material in order to form two concentric seals.
 7. Asuspension stop device according to claim 1, characterized in that ametal raceway is inserted between the two upper and lower cases (21, 23)of the suppression block (20) at the level of the circular hollows, thisraceway being composed of two upper and lower parts (31, 32) seatedrespectively against the opposite faces of the two cases.
 8. Asuspension stop device according to claim 1, characterized in that acylindrical metal distance piece (47) is placed along the shock-absorberrod (24), between it on the one hand and the upper case (21) and theelastomeric crown (45) of the suppression block (20) on the other hand,and in that a nut (28) is tightened around the axis (67) of the rod (24)to fix the upper case (21) to the body (48) of the vehicle.